.NET Core, ASP.NET Core RC2 Available This Week

Secondary previews of ASP.NET Core 1.0 and .NET Core 1.0 are being released this week by Microsoft's .NET engineering team. RC2 versions is mainly polishing up of performance and reliability issues, but Microsoft says that these versions are live and production-capable.

"You can use it to build ASP.NET Core, console apps and class libraries for Windows, OS X and Linux," writes Microsoft's Rich Lander, in a blog post. "RC2 is a major update from the November RC1 release, including new APIs, performance and reliability improvements and a new set of tools."

Some of the polish in .NET Core RC2 includes more a rollup of Linux platform support. More recently, Debian 8.2 support was added, but it also supports Ubuntu 14.04, Red Hat Enterprise Linux 7.2, and Centos 7.1. With Microsoft's tighter partnership, .NET Core RC2 will be available through Red Hat's software collection resource.

.NET Core RC2 also includes a number of improvements, such as a new dotnet tool, which is a replacement for the dnx and dnu tools that were available in RC1; improvements to the RyuJIT just in time compiler; ability to do garbage collection on Unix OSes in the background; and a new runtime configuration approach, wherein runtime configuration files store app dependency info.

A preview of the .NET Core SDK is also being made available, which developers can use on Windows, Linux, and OS X, and Docker containers. Lander notes that is being tagged as a Preview 1 rather than an RC2, since it "includes enough software to build an app," but not enough changes that push it into release candidate status. One addition is a telemetry feature, which is turned on by default and collects and passes data anonymously back to the team, which Microsoft publishes in an aggregated form from all sources. Naturally, the telemetry feature can be switched off.

Microsoft's Jeffrey Fritz, in another blog, details many of the feature additions to ASP.NET Core 1.0 RC2, which includes a key addition: .NET CLI. "This tool replaces the dnvm, dnx, and dnu utilities with a single tool that handles the responsibilities of these tools," he explains. He also notes that ASP.NET Core RC2 now runs as a .NET Core Console app rather than as a class library.

"As of RC2 an ASP.NET Core application is a .NET Core Console application that calls into ASP.NET specific libraries," writes Fritz. "What this means for ASP.NET Core apps is that the code that used to live in the ASP.NET Hosting libraries and automatically run your startup.cs now lives inside a Program.cs. This alignment means that a single .NET toolchain can be used for both .NET Core Console applications and ASP.NET Core applications."

Later this week, Fritz said that ASP.NET Core RC2 will be available for use in Azure Web applications. He links to a number of resources for migrating to RC2 at the end of his post.

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